To improve storage system availability, a copy pair is formed between a plurality of storage devices for a volume that is used by a business program running on a host computer (hereinafter, host). A target storage device allows alternate path software on the host to recognize a communication path (also called a host path hereinbelow) for accessing a target volume as the host path for accessing a source volume. The alternate path software controls which host path, of a plurality of host paths capable of being used to access a volume, will be used.
In a case where all the host paths to the source volume have been blocked as a result of damage or human error on the part of an administrator, a path switching function of the alternate path software switches from the host path to the source volume to a host path to the target volume. In accordance with this, a high-availability computer system that allows a user to continue working has been proposed (Patent Literature 1).
There are also cases in which a configuration change that impacts the access performance of the source volume, such as a change in the bandwidth setting of the communication port for the source volume or a setting change to the cache capacity allocated to the source volume, is requested. In a case like this, the configuration of the target volume is also changed to coincide with the configuration change of the source volume. In accordance with this, the source volume and the target volume are provided with the same configuration. Therefore, technology that guarantees the same access performance as that when the source volume is used even in the case of a failover from the source volume to the target volume has been proposed (Patent Literature 2).